As an example of cutting inserts, Japanese Unexamined Patent Publication No. 2004-284010 discloses a reversible cut insert having a rectangular shape in a top view. The cut insert has a structure in which a basal body is twisted around two axial lines.
However, when an attempt is made to ensure a large axial rake angle of a cutting edge in the foregoing cut insert, it is necessary to decrease a forward inclination angle of the cut insert. This makes it difficult to ensure a sufficient clearance angle between a flank surface and a workpiece during a cutting process. Consequently, frictional heat generation occurs due to contact between the flank surface and the workpiece, and there is a risk of early wear of the cut insert.